Super-Kamiokande

Using the timing and charge information recorded by each PMT, the interaction vertex, ring direction, and flavor of the incoming neutrino is determined.

[citation needed] Construction of the predecessor of the present Kamioka Observatory, the Institute for Cosmic Ray Research, University of Tokyo began in 1982 and was completed in April 1983.

The Super-Kamiokande project was approved by the Japanese Ministry of Education, Science, Sports and Culture in 1991 for total funding of approximately $100 million.

The American portion of the proposal, which was primarily to build the OD system, was approved by the United States Department of Energy in 1993 for $3 million.

[14] The detector was partially restored by redistributing the photomultiplier tubes which did not implode, and by adding protective acrylic shells that are hoped will prevent another chain reaction from recurring (Super-Kamiokande-II).

[15] In 2020, the detector was upgraded for the SuperKGd project by adding a gadolinium salt to the ultrapure water in order to enable the detection of antineutrinos from supernova explosions.

There were two pairs of QAC/TAC for each PMT input signal, this prevented dead time and allowed the readout of multiple sequential hits that may arise, e.g., from electrons that are decay products of stopping muons.

[17] Gadolinium was introduced into the Super-Kamiokande water tank in 2020 in order to distinguish neutrinos from antineutrinos that arise from supernova explosions.

Antineutrinos produce a double flash of light about 30 microseconds apart, first when the neutrino hits a proton and second when gadolinium absorbs a neutron.

It finished operation in 2018 and showed that the new water purification system would remove impurities while keeping the gadolinium concentration stable.

It also showed that gadolinium sulfate would not significantly impair the transparency of the otherwise ultrapure water, or cause corrosion or deposition on existing equipment or on the new valves that will later be installed in the Hyper-Kamiokande.

To protect against low-energy background radiation from radon decay products in the air, the roof of the cavity and the access tunnels were sealed with a coating called Mineguard.

Mineguard is a spray-applied polyurethane membrane developed for use as a rock support system and radon gas barrier in the mining industry.

[12] A standard fiducial volume of approximately 22.5 kilotonnes is defined as the region inside a surface drawn 2.00 m from the ID wall to minimize the anomalous response caused by natural radioactivity in the surrounding rock.

[12] To detect and identify such bursts as efficiently and promptly as possible Super-Kamiokande is equipped with an online supernova monitor system.

If the burst candidate passes these checks, the data will be reanalyzed using an offline process and a final decision will be made within a few hours.

This monitor allows non-expert shift physicists to identify and repair common problems to minimize down time, and the software package was a significant contribution to the smooth operation of the experiment and its overall high lifetime efficiency for data taking.

[12] The energy of the Sun comes from the nuclear fusion in its core where a helium atom and two electron neutrinos are generated by 4 protons.

Photons, created by the nuclear fusion in the center of the Sun, take millions of years to reach the surface; on the other hand, solar neutrinos arrive at the earth in eight minutes due to their lack of interactions with matter.

Hence, solar neutrinos make it possible for us to observe the inner Sun in "real-time" that takes millions of years for visible light.

But in aggregate, the Cl, Kamioka II, and Ga experiments indicated a pattern of neutrino fluxes that was not compatible with any adjustment of the SSM.

The Super-K detector will record the Cherenkov radiation of muons and electrons created by interactions between high-energy neutrinos and water.

However, the Grand Unified Theories (GUTs) predict that protons can decay into lighter energetic charged particles such as electrons, muons, pions, or others which can be observed.

Now, raw mine water is recycled through the first step (particle filters and RO) for some time before other processes, which involve expensive expendables, are imposed.

[12] A heat exchanger is used to cool down the water in order to reduce the PMT dark noise level as well as suppress the growth of bacteria.

This low level satisfies that goals of air quality so that carbon filter regeneration operations would no longer be required.

The offline data processing system is located in Kenkyuto and is connected to Super-Kamiokande detector with 4 km FDDI optical fiber link.

[12] Offline system was designed to meet demand of all these: tape storage of a large database (14 Tbytes yr−1), stable semi-realtime processing, nearly continuous re-processing and Monte Carlo simulation.

The computer system consists of three major sub-systems: the data server, the CPU farm, and the network at the end of Run I.

[34] In September 2018, the detector was drained for maintenance, affording a team of Australian Broadcasting Corporation reporters the opportunity to obtain 4K resolution video from within the detection tank.